Project description:Objective: Systemic lupus erythematosus (SLE) has limited monozygotic (MZ) twin concordance, implying a role for other pathogenic factors than genetic variation, such as epigenetic changes. Using the disease discordant twin model, we investigated genome-wide DNA methylation changes in sorted CD4+ T-cells, monocytes, granulocytes and B-cells in twin pairs with at least one SLE-affected twin. Methods: Peripheral blood from 15 SLE twin pairs (six MZ, nine dizygotic (DZ)) was processed using gradient density centrifugation for the granulocyte fraction. CD4+ T-cells, monocytes and B-cells were further isolated using magnetic beads. Genome-wide DNA methylation was analysed using Infinium HumanMethylation450K BeadChips. Probes with a p-value <0.01 between SLE twins and co-twins were considered statistically significant and a median DNA methylation difference >7% biologically relevant. Findings were validated using pyrosequencing and replicated in an independent case-control sample. Results: In paired analyses of discordant SLE twins restricted to the gene promoter and start region, we identified 55, 327, 247 and 1628 genes with differentially methylated CpGs in CD4+ T-cells, monocytes, granulocytes and B-cells, respectively. All cell types displayed marked hypomethylation in interferon-regulated genes, such as IFI44L, PARP9 and IFITM1, which was more pronounced in twins with flare within the past two years. In contrast to the other cell types, differentially methylated CpGs in B-cells were predominantly hypermethylated, where the most important upstream regulators included TNF and EP300. Conclusion: Hypomethylation of interferon-regulated genes occurs in all major cellular compartments in SLE twins. The observed B-cell promoter hypermethylation is a novel finding with potential significance for SLE pathogenesis. Overall design: Fifteen Danish twin pairs were included in the study, 13 twin pairs are submitted to GEO (excluding two concordant twin pairs).

Project description:DNA (cytosine-5) methyltransferase 1 (DNMT1) is essential for mammalian development and maintenance of DNA methylation following DNA replication in cells. The DNA methylation process generates S-adenosyl-L-homocysteine, a strong inhibitor of DNMT1. Here we report that S-adenosylhomocysteine hydrolase (SAHH/AHCY), the only mammalian enzyme capable of hydrolyzing S-adenosyl-L-homocysteine binds to DNMT1 during DNA replication. SAHH activates DNMT1 in vitro and its overexpression in mammalian cells leads to hypermethylation of the genome, whereas its inhibition by adenosine periodate resulted in hypomethylation of the genome. Hypermethylation was consistent in both gene bodies and repetitive DNA elements leading to both down- and up-regulation of genes. Similarly, hypomethylation led to both up- and down-regulation of genes suggesting methylated regions influence gene expression either positively or negatively. Cells overexpressing SAHH specifically up-regulated metabolic pathway genes and down-regulated PPAR and MAPK signaling pathways genes. Therefore, we suggest that alteration of SAHH level in the cell leads to aberrant DNA methylation, altered metabolite levels and gene expression.

Project description:The objective of this study was to analyze genome-wide differential methylation patterns in maternal leukocyte DNA in early pregnant and non-pregnant states. This is an age- and body mass index-matched case-control study comparing the methylation patterns of 27,578 cytosine-guanine (CpG) sites in 14,495 genes in maternal leukocyte DNA in early pregnancy (n=14), in the same women postpartum (n=14), and in nulligravid women (n=14) on a BeadChip platform. Transient widespread hypomethylation was found in early pregnancy as compared with the non-pregnant states. Methylation of nine genes was significantly different in early pregnancy compared to both postpartum and nulligravid states (< 10% False Discovery Rate). Early pregnancy may be characterized by widespread hypomethylation compared to non-pregnant states; there is no apparent permanent methylation imprint after a normal-term gestation. Nine potential candidate genes were identified as differentially methylated in early pregnancy and may play a role in the maternal adaptation to pregnancy. Overall design: This is an age- and body mass index-matched case-control study comparing the methylation patterns of 27,578 cytosine-guanine (CpG) sites in 14,495 genes in maternal leukocyte DNA in early pregnancy (n=14), in the same women postpartum (n=14), and in nulligravid women (n=14) on a BeadChip platform.

Project description:The objective of this study was to analyze genome-wide differential methylation patterns in maternal leukocyte DNA in early pregnant and non-pregnant states. This is an age- and body mass index-matched case-control study comparing the methylation patterns of 27,578 cytosine-guanine (CpG) sites in 14,495 genes in maternal leukocyte DNA in early pregnancy (n=14), in the same women postpartum (n=14), and in nulligravid women (n=14) on a BeadChip platform. Transient widespread hypomethylation was found in early pregnancy as compared with the non-pregnant states. Methylation of nine genes was significantly different in early pregnancy compared to both postpartum and nulligravid states (< 10% False Discovery Rate). Early pregnancy may be characterized by widespread hypomethylation compared to non-pregnant states; there is no apparent permanent methylation imprint after a normal-term gestation. Nine potential candidate genes were identified as differentially methylated in early pregnancy and may play a role in the maternal adaptation to pregnancy. This is an age- and body mass index-matched case-control study comparing the methylation patterns of 27,578 cytosine-guanine (CpG) sites in 14,495 genes in maternal leukocyte DNA in early pregnancy (n=14), in the same women postpartum (n=14), and in nulligravid women (n=14) on a BeadChip platform.

Project description:Global DNA hypomethylation in CD4+ cells in SLE patients was suggested to play a key role in the pathogenesis. To identify new methylation-sensitive genes, we integrated genome-wide DNA methylation and mRNA profiling in CD4+ cells of MRL/lpr (MRL) and C57BL6/J (B6) mice. We identified Ctse, in which 13 methyl-CpGs within 583 bp region of intron 1 were hypomethylated, and mRNA upregulated in MRL compared with B6 mice. One of methyl-CpGs, mCGCG was hypomethylated and mutated to CGGG in MRL mice. Kaiso is known to bind mCGCG and we hypothesized that it represses expression of Ctse. The binding of Kaiso to mCGCG site in B6 was reduced in MRL mice revealed by ChIP-PCR. EL4 cells treated with 5-azaC and/or TSA showed the suppression of the binding of Kaiso to mCGCG motif and the overexpression of Ctse was demonstrated by qPCR. Ctse gene silencing by siRNA in EL4 cells resulted in reduction of IL-10 secretion. Accordingly, IL10 and CTSE mRNAs up-regulated in CD4+ T cells both in MRL mice and the patients with SLE. The hypomethylation of mCGCG motif, reduced recruitment of Kaiso, and increased expression of Ctse and Il-10 in CD4+ cells may be involved in the pathogenesis of SLE. Overall design: To identify new candidate genes regulated by DNA methylation and involved in the pathogenesis of systemic lupus erythematosus (SLE), we performed Illumina Hiseq to analyze the genome-wide DNA methylation and expression of mRNA of CD4+ T cell isolated from spleens in MRL/lpr-Tnfrsf6lpr (MRL) mice and C57BL/6J (B6) mice. Both mice are female, 16 weeks old. For Illumina analysis, we used one mouse of MRL mice and one mouse of B6 mice.

Project description:Cytosine methylation silences transposable elements in plants, vertebrates and fungi, but also regulates gene expression1. Plant methylation is catalyzed by three families of enzymes, each with a preferred sequence context: CG, CHG (H = A, C or T) and CHH, with CHH methylation targeted by the RNA interference (RNAi) pathway2. Arabidopsis thaliana endosperm, a placenta-like tissue that nourishes the embryo, is globally hypomethylated in the CG context while retaining high non-CG methylation3. Global methylation dynamics in seeds of cereal crops that provide the bulk of human nutrition remain unknown. Here we show that rice endosperm DNA is hypomethylated in all sequence contexts. Non-CG methylation is reduced evenly across the genome, while CG hypomethylation is localized. CHH methylation of small transposable elements is increased in embryos, suggesting that endosperm demethylation enhances transposon silencing. Genes preferentially expressed in endosperm, including those coding for major storage proteins and starch synthesizing enzymes, are frequently hypomethylated in endosperm, indicating that DNA methylation is a crucial regulator of rice endosperm biogenesis. Our data demonstrate that genome-wide reshaping of seed DNA methylation is conserved among angiosperms and has a profound effect on gene expression in cereal crops. Keywords: Epigenetics Overall design: Examination of DNA methylation in rice

Project description:Determination of the profile of genes commonly aberrantly methylated in colorectal cancer (CRC) has substantial potential value for diagnostic and therapeutic application. However, our knowledge of the DNA methylation pattern in CRC is currently limited. Therefore, we analyzed the methylation profile of 27,578 CpG sites spanning more than 14,000 genes in CRC and in adjacent normal mucosa using beadchip array-based technology. We identified 621 CpG sites located in promoter region and CpG islands that were significantly hypermethylated in CRC compared to normal mucosa. Genes on chromosome 18 showed promoter hypermethylation most frequently. According to gene ontology analysis, the most common biologically relevant class of genes affected by methylation was the class associated with the cadherin signaling pathway. In comparison with genome-wide expression array, mRNA expression was more like to be down-regulated in the genes demonstrating promoter hypermethylation, although this was not statistically significant. We validated 10 CpG sites that were shown to be hypermethylated in the array studies (ADHFE1, BOLL, SLC6A15, ADAMTS5, TFPI2, EYA4, NPY, TWIST1, LAMA1, GAS7) and 2 CpG sites showing hypomethylaion (MAEL, SFT2D3) in CRC compared to normal mucosa using pyrosequencing. The methylation status measured by pyrosequencing was consistent with the methylation array data. In conclusion, we have shown that methylation profiling based on beadchip arrays is an effective method for screening for aberrantly methylated genes in CRC. In addition, we identified novel methylated genes that are candidate diagnostic or prognostic markers for CRC. Overall design: We measured the methylation status of the 27,578 CpG sites (Human Methylation27 DNA Analysis BeadChip) in 22 pairs of CRC tissue and adjacent normal mucosa to identify genes that are commonly aberrantly methylated in CRC.

Project description:Cytosine methylation silences transposable elements in plants, vertebrates and fungi, but also regulates gene expression1. Plant methylation is catalyzed by three families of enzymes, each with a preferred sequence context: CG, CHG (H = A, C or T) and CHH, with CHH methylation targeted by the RNA interference (RNAi) pathway2. Arabidopsis thaliana endosperm, a placenta-like tissue that nourishes the embryo, is globally hypomethylated in the CG context while retaining high non-CG methylation3. Global methylation dynamics in seeds of cereal crops that provide the bulk of human nutrition remain unknown. Here we show that rice endosperm DNA is hypomethylated in all sequence contexts. Non-CG methylation is reduced evenly across the genome, while CG hypomethylation is localized. CHH methylation of small transposable elements is increased in embryos, suggesting that endosperm demethylation enhances transposon silencing. Genes preferentially expressed in endosperm, including those coding for major storage proteins and starch synthesizing enzymes, are frequently hypomethylated in endosperm, indicating that DNA methylation is a crucial regulator of rice endosperm biogenesis. Our data demonstrate that genome-wide reshaping of seed DNA methylation is conserved among angiosperms and has a profound effect on gene expression in cereal crops. Keywords: Epigenetics Examination of DNA methylation in rice